AHL Content Statements

• D1.3.8

  Gene knockout as a technique for investigating the function of a gene by changing it to make it inoperative
  

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  Students are not required to know details of techniques. Students should appreciate that a library of knockout organisms is available for some species used as models in research.

• D1.3.9

  Use of the CRISPR sequences and the enzyme Cas9 in gene editing

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  Students are not required to know the role of the CRISPR–Cas system in prokaryotes. However, students should be familiar with an example of the successful use of this technology.
  NOS: Certain potential uses of CRISPR raise ethical issues that must be addressed before implementation. Students should understand that scientists across the world are subject to different regulatory systems. For this reason, there is an international effort to harmonize regulation of the application of genome editing technologies such as CRISPR.
  

• D1.3.10

  Hypotheses to account for conserved or highly conserved sequences in genes

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  Conserved sequences are identical or similar across a species or a group of species; highly conserved sequences are identical or similar over long periods of evolution. One hypothesis for the mechanism is the functional requirements for the gene products and another hypothesis is slower rates of mutation.